Charging devices for shaft furnaces



CHARGING DEVICES FOR SHAFT FURNACES Filed Dec. 16, 1957 2 Sheets-Sheet; 1

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(TL-- a INVENTOR ISAK EDVIN J'OHANSSON BUCKHORN,CHEATHAM & BLORE ATTORNEVJ Dec. 20, 1960 I. E. JOHANSSON 2,965,250

CHARGING DEVICES FOR SHAFT FURNACES Filed Dec. 16, 1957 2 Sheets-Sheet 2 lNVENTOR ISAK EDVIN J'OHANSSON BUCKHORN,CHEATHAM 8.8LORE CHARGING DEVICES FOR SHAFT FURNACES Isak Edvin Johansson, Stockholm, Sweden, assignor to T. An. Tesch Aktiebolag, Stockholm, Sweden, a corporation of Sweden Filed Dec. 16, 1957, Ser. No. 703,203

Claims priority, application Sweden Oct. 15, 1957 3 Claims. (Cl. 21436) The present invention relates to charging devices for shaft furnaces and is more particularly concerned with means to provide a gas-tight seal between the furnace and the charging device.

In charging devices for shaft furnaces it is known to arrange the bottom closing means of the charging device with two cones or bells disposed one above the other, the lower bell in some positions being partly enclosed in the upper bell. When dumping charge stock from the charging device to the furnace, both bells may be raised within the charging device, the stock thereby dropping through the uncovered bottom opening in the charging device to a central zone of the furnace, or the lower bell may first be lowered into the furnace and thereupon the upper bell raised within the charging device. In that case the stock dropping from the bottom opening of the charging device impinges on the lower bell and slides along the sides of the bell to be deposited in the furnace around the circumference thereof. It is also known to arrange within the furnace a stock distributor or a plurality of stock distributors disposed one above the other, through the central opening of which the lower bell may pass. The stock distributors are so constructed that when the bell is set so that its lower circumferential edge closes the opening of the stock distributor, the stock distributor serves as an extension of the bell, whereby the stock sliding along the bell and the stock distributor will be passed toward the circumference of the furnace.

Sealing against leakage of gas from the furnace to the charging device, when dumping of stock into the furnace does not take place, is achieved by the upper bell which in its lower position engages sealingly the bottom of the charging device around the bottom opening. The lower bell which is to be lifted within the charging device and lowered into the furnace must have a smaller diameter than the bottom opening of the charging device. In this known construction, it is diflicult, in particular in furnaces operating at a high inner gas pressure (1 atmosphere above atmospheric pressure or more) to obtain a satisfactory sealing against gas leaking from the furnace to the charging device since the gas pressure tends to lift the upper bell, wherefore this must be made so heavy that the operation of the bell is rendered difficult.

The main object of the present invention is to overcome this disadvantage and provide a charging device which is effectively sealed against gas leakage from the furnace without the necessity of making the upper bell unduly heavy. This is achieved by making the lower bell with a greater diameter than the bottom opening of the charging device, whereby the lower bell is always disposed with its lower part below the charging device. The lower bell and the lower edge of the bottom opening are so devised that sealing between the furnace and the charging device is achieved when the lower bell is in its highest position, the sealing effect being improved by the gas pressure in the furnace act- 2,965,250 Patented Dec. 20, 1960 ing to keep the bell in engagement with the bottom of the charging device.

Since in this arrangement, the lower bell cannot be lifted into the charging device, the stock cannot be charged to the central portion of the furnace. Preferably, therefore, there is arranged within the stock distributor in the furnace or within the lowest stock distributor, when there are more than one stock distributor, a number of inwardly inclined stock guiding members which direct a portion of the stock towards the center of the furnace. The gaps provided between the stock guiding members are sufficiently great that the stock will not be separated into fractions of different particle sizes.

The invention will be explained more in detail below with reference to the accompanying drawings which illustrate somewhat diagrammatically two embodiments of the invention.

Figure 1 shows partly in vertical cross-section the top of a shaft furnace equipped with a charging device in accordance with this invention.

Figure 2 is a fragmentary cross-sectional view illustrating how the bells are arranged relative to the bottom opening.

Figure 3 shows, partly in vertical cross-section, another embodiment of a shaft furnace equipped with the charging device of this invention.

Figure 4 shows a horizontal cross-section of the stock distributor in the embodiment of Figure 3.

In all the figures, the reference character A designates a shaft furnace, which has a lining 21 and is equipped with a charging device comprising a stationary lower hopper B and a rotatable upper hopper C. The stock to be charged is delivered to the hopper C by the skip car 1. When the hopper C is filled with stock, it is turned through a certain angle ditferent for different loads in accordance with a predetermined program. Turning of the hopper is effected by means of an electric motor 2, a worm gear 3, toothed wheels 4 and a toothed ring 5. The rotatable hopper C is carried by a number of rolls 6. After turning of the hopper, the hell 7 is lowered, whereby the stock is dumped from the hopper C into the hopper B. The hell 7 is supported by a tubular rod 8, a cable 9 and a sheave 10.

The frusto-conical bottom 11 of the hopper B has a central opening which is closed from above by a bell 12 and from below by a bell 13, when these bells are in their closing positions. The bell 12 is carried by a tubular rod 14, which is disposed within the rod 8, a cable 15 and a sheave 16. The bell 13 is carried by a rod 17 disposed within the tubular rod 14, a cable 18 and a sheave 19.

In the embodiment of Figure 1, there is arranged in the top of the furnace below the hopper B, two concentric frustoconical annular stock distributors 20 and 22, the central openings of which have a diameter slightly greater than the diameter of the lower bell 13, so that the hell can pass therethrough. The inclination of the stock distributors is such that when the lower bell 13 is set with its lower edge at a level with the central opening of a stock distributor, this forms an extension of the bell serving to guide the stock toward the circumference of the furnace, as will be explained below.

In the embodiment of Figures 3 and 4, there is provided a single stock distributor 23 similar to the above stock distributors 20 and 22. A number of peripherally spaced stock guiding members or baffles 24 extend from the inner side of the stock distributor 23 near its lower edge downwards and inwards toward the center of the furnace.

The rods 8, 14 and 17 are guided and fixed against The gas When-thestock is to be dumped from the hopper B to the furnace A, the bell 13 will first be lowered to one of the "positions 13a, 13b and 130 in Figure 1 or 13d or 13's in Figure 3. Thereupon, the bell 12 is lifted to the position 12a. It will be understood that lowering andli-fting'of the bells 12 and 13 as well as the bell 7 will take place by means of suitable means (not shown) acting on the cables 9, 15 and 18. The stock in the hopper B will then pass to the furnace A and is distributed as follows:

In the embodiment of Figure 1.When the bell 13 is set in the position 13a, the stock slides along the bell and further along the upper stock distributor and is deposited circumferentially along the lining 21 of the furnace. When the bell 13 is set in the position 13b the stock slides along the hell and further along the lower stock distributor 22 and is deposited concentrically with the lining 21 in an intermediate Zone. When the bell 13 is set in the position 130 the stock slides along the bell and is deposited in the furnace A closer to the middle of the'furnace.

In the embodiment of Figure 3.-When the bell 13 is set in the position 13d, the stock slides along the bell and further along the stock distributor 23 and isdeposited circumferentially around the lining -21 of the furnace. When the bell is set in the position 13c, the stock slides along the bell and a portion of the stock is directed by the stock guiding members 24 towards the middle of the furnace, while the remainder passes through the gaps between the stock guiding members and is deposited in an intermediate zone concentric with the furnace.

While two specific embodiments have been illustrated and described above, it will be obvious to those skilled in-the art that various modifications thereof are possible without departing from the spirit and scope of this invention.

Iclaim:

l. A charging device for shaft furnaces comprising a frusto-conical hopper havinga circular bottom opening, an upper bell of a diameter greater than'that of said opening adapted to engage the wall of said hopper immediately above said'opening soas to close said bottom opening, means for lifting said upper bell above its closing position to permit dumping 'of stock from the hopper to the furnace, a lower bell having a diameter greater than that of the bottom opening of the hopper and adapted to engage the lower edge of the bottom opening sealingly to prevent leakage of gas from the furnace to the hopper, said lower bell being capable of engaging said edge while said upper bell is in said closing position, means for lowering said lower bell to various positions below its closing position to permit dumping of stock from thehopper to the furnace, andat least one conical stock distributor having-a central opening and disposed below the hopper to cooperate with said lower bell in its lowered position to guide the stock to a predetermined zone in the furnace.

2. A charging device as in claim 1, in which inside the lowest stock distributor there is disposed a number of inwardly directed stock guiding members adapted to direct a portion of the stock towards the center of the furnace, said stock guiding members being spaced sufficiently from each other to prevent separation of the stock into fractions with different particle sizes.

3. A charging device for shaft furnaces comprising a frusto-conical hopper having a circular bottom opening, an upper bell of a diameter greater than'that'o'f said opening and adapted to engage the wall of said hopperimmediately above said opening so as to close saidbottom opening, means for lifting said upper bell above its closing position to permit dumping ofstock from the hopper to the furnace, a lower bell having a diameter greater than that of said opening and adapted sealingly to engage the lower edge of the bottom opening to prevent leakage of gas from the furnace to said hopper, and means for lowering said lower bell below its closing position to permit dumping of stock from the furnace, said lower bell being capable of engaging said edge while said upper bell is in said closing position.

References Cited in the file of this patent UNITED STATES PATENTS 4F,849 Conner Oct. 6, 1891 864,053 Witherbee Aug.20, 1907 1,267,005 Slick May 21, 1918 1,868,870 Barr July 26, 1932 2,667,278 Tesch et al. Jan. 26; 1954 FOREIGN PATENTS 311,601 Germany Apr. 3, 1919 

